/*
 * FreeRTOS Kernel V10.3.1
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://www.FreeRTOS.org
 * http://aws.amazon.com/freertos
 *
 * 1 tab == 4 spaces!
 */

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"

/* The critical nesting value is initialised to a non zero value to ensure
 * interrupts don't accidentally become enabled before the scheduler is started. */
#define portINITIAL_CRITICAL_NESTING    ( ( uint16_t ) 10 )

/* Initial PSW value allocated to a newly created task.
 *   1100011000000000
 *   ||||||||-------------- Fill byte
 *   |||||||--------------- Carry Flag cleared
 *   |||||----------------- In-service priority Flags set to low level
 *   ||||------------------ Register bank Select 0 Flag cleared
 *   |||------------------- Auxiliary Carry Flag cleared
 *   ||-------------------- Register bank Select 1 Flag cleared
 *   |--------------------- Zero Flag set
 *   ---------------------- Global Interrupt Flag set (enabled)
 */
#define portPSW                         ( 0xc6UL )

/* The address of the pxCurrentTCB variable, but don't know or need to know its
 * type. */
typedef void TCB_t;
extern volatile TCB_t * volatile pxCurrentTCB;

/* Each task maintains a count of the critical section nesting depth.  Each time
 * a critical section is entered the count is incremented.  Each time a critical
 * section is exited the count is decremented - with interrupts only being
 * re-enabled if the count is zero.
 *
 * usCriticalNesting will get set to zero when the scheduler starts, but must
 * not be initialised to zero as that could cause problems during the startup
 * sequence. */
volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;

/*-----------------------------------------------------------*/

/*
 * Sets up the periodic ISR used for the RTOS tick using the interval timer.
 * The application writer can define configSETUP_TICK_INTERRUPT() (in
 * FreeRTOSConfig.h) such that their own tick interrupt configuration is used
 * in place of prvSetupTimerInterrupt().
 */
static void prvSetupTimerInterrupt( void );
#ifndef configSETUP_TICK_INTERRUPT

/* The user has not provided their own tick interrupt configuration so use
 * the definition in this file (which uses the interval timer). */
    #define configSETUP_TICK_INTERRUPT()    prvSetupTimerInterrupt()
#endif /* configSETUP_TICK_INTERRUPT */

/*
 * Defined in portasm.s87, this function starts the scheduler by loading the
 * context of the first task to run.
 */
extern void vPortStartFirstTask( void );

/*
 * Used to catch tasks that attempt to return from their implementing function.
 */
static void prvTaskExitError( void );

/*-----------------------------------------------------------*/

/*
 * Initialise the stack of a task to look exactly as if a call to
 * portSAVE_CONTEXT had been called.
 *
 * See the header file portable.h.
 */
StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
                                     TaskFunction_t pxCode,
                                     void * pvParameters )
{
    uint32_t * pulLocal;

    /* With large code and large data sizeof( StackType_t ) == 2, and
    * sizeof( StackType_t * ) == 4.  With small code and small data
    * sizeof( StackType_t ) == 2 and sizeof( StackType_t * ) == 2. */

    #if __DATA_MODEL__ == __DATA_MODEL_FAR__
        {
            /* Parameters are passed in on the stack, and written using a 32-bit value
             * hence a space is left for the second two bytes. */
            pxTopOfStack--;

            /* Write in the parameter value. */
            pulLocal = ( uint32_t * ) pxTopOfStack;
            *pulLocal = ( uint32_t ) pvParameters;
            pxTopOfStack--;

            /* The return address, leaving space for the first two bytes of	the
             * 32-bit value.  See the comments above the prvTaskExitError() prototype
             * at the top of this file. */
            pxTopOfStack--;
            pulLocal = ( uint32_t * ) pxTopOfStack;
            *pulLocal = ( uint32_t ) prvTaskExitError;
            pxTopOfStack--;

            /* The start address / PSW value is also written in as a 32-bit value,
             * so leave a space for the second two bytes. */
            pxTopOfStack--;

            /* Task function start address combined with the PSW. */
            pulLocal = ( uint32_t * ) pxTopOfStack;
            *pulLocal = ( ( ( uint32_t ) pxCode ) | ( portPSW << 24UL ) );
            pxTopOfStack--;

            /* An initial value for the AX register. */
            *pxTopOfStack = ( StackType_t ) 0x1111;
            pxTopOfStack--;
        }
    #else /* if __DATA_MODEL__ == __DATA_MODEL_FAR__ */
        {
            /* The return address, leaving space for the first two bytes of	the
             * 32-bit value.  See the comments above the prvTaskExitError() prototype
             * at the top of this file. */
            pxTopOfStack--;
            pulLocal = ( uint32_t * ) pxTopOfStack;
            *pulLocal = ( uint32_t ) prvTaskExitError;
            pxTopOfStack--;

            /* Task function.  Again as it is written as a 32-bit value a space is
             * left on the stack for the second two bytes. */
            pxTopOfStack--;

            /* Task function start address combined with the PSW. */
            pulLocal = ( uint32_t * ) pxTopOfStack;
            *pulLocal = ( ( ( uint32_t ) pxCode ) | ( portPSW << 24UL ) );
            pxTopOfStack--;

            /* The parameter is passed in AX. */
            *pxTopOfStack = ( StackType_t ) pvParameters;
            pxTopOfStack--;
        }
    #endif /* if __DATA_MODEL__ == __DATA_MODEL_FAR__ */

    /* An initial value for the HL register. */
    *pxTopOfStack = ( StackType_t ) 0x2222;
    pxTopOfStack--;

    /* CS and ES registers. */
    *pxTopOfStack = ( StackType_t ) 0x0F00;
    pxTopOfStack--;

    /* The remaining general purpose registers DE and BC */
    *pxTopOfStack = ( StackType_t ) 0xDEDE;
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xBCBC;
    pxTopOfStack--;

    /* Finally the critical section nesting count is set to zero when the task
     * first starts. */
    *pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;

    /* Return a pointer to the top of the stack that has been generated so it
     * can	be stored in the task control block for the task. */
    return pxTopOfStack;
}
/*-----------------------------------------------------------*/

static void prvTaskExitError( void )
{
    /* A function that implements a task must not exit or attempt to return to
     * its caller as there is nothing to return to.  If a task wants to exit it
     * should instead call vTaskDelete( NULL ).
     *
     * Artificially force an assert() to be triggered if configASSERT() is
     * defined, then stop here so application writers can catch the error. */
    configASSERT( usCriticalNesting == ~0U );
    portDISABLE_INTERRUPTS();

    for( ; ; )
    {
    }
}
/*-----------------------------------------------------------*/

BaseType_t xPortStartScheduler( void )
{
    /* Setup the hardware to generate the tick.  Interrupts are disabled when
     * this function is called. */
    configSETUP_TICK_INTERRUPT();

    /* Restore the context of the first task that is going to run. */
    vPortStartFirstTask();

    /* Execution should not reach here as the tasks are now running!
     * prvSetupTimerInterrupt() is called here to prevent the compiler outputting
     * a warning about a statically declared function not being referenced in the
     * case that the application writer has provided their own tick interrupt
     * configuration routine (and defined configSETUP_TICK_INTERRUPT() such that
     * their own routine will be called in place of prvSetupTimerInterrupt()). */
    prvSetupTimerInterrupt();
    return pdTRUE;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
    /* It is unlikely that the RL78 port will get stopped. */
}
/*-----------------------------------------------------------*/

static void prvSetupTimerInterrupt( void )
{
    const uint16_t usClockHz = 15000UL; /* Internal clock. */
    const uint16_t usCompareMatch = ( usClockHz / configTICK_RATE_HZ ) + 1UL;

    /* Use the internal 15K clock. */
    OSMC = ( uint8_t ) 0x16;

    #ifdef RTCEN
        {
            /* Supply the interval timer clock. */
            RTCEN = ( uint8_t ) 1U;

            /* Disable INTIT interrupt. */
            ITMK = ( uint8_t ) 1;

            /* Disable ITMC operation. */
            ITMC = ( uint8_t ) 0x0000;

            /* Clear INIT interrupt. */
            ITIF = ( uint8_t ) 0;

            /* Set interval and enable interrupt operation. */
            ITMC = usCompareMatch | 0x8000U;

            /* Enable INTIT interrupt. */
            ITMK = ( uint8_t ) 0;
        }
    #endif /* ifdef RTCEN */

    #ifdef TMKAEN
        {
            /* Supply the interval timer clock. */
            TMKAEN = ( uint8_t ) 1U;

            /* Disable INTIT interrupt. */
            TMKAMK = ( uint8_t ) 1;

            /* Disable ITMC operation. */
            ITMC = ( uint8_t ) 0x0000;

            /* Clear INIT interrupt. */
            TMKAIF = ( uint8_t ) 0;

            /* Set interval and enable interrupt operation. */
            ITMC = usCompareMatch | 0x8000U;

            /* Enable INTIT interrupt. */
            TMKAMK = ( uint8_t ) 0;
        }
    #endif /* ifdef TMKAEN */
}
/*-----------------------------------------------------------*/
